Add the ability to set the format in the decorator

Geckoboard has deprecated the parameter passing (although it can still be enabled). This change allows you to set
the response format like this:

```python
@NumberWidget(format='json')
def my_view_fun():
  ...
```

django_geckoboard/decorators.py

@@ -38,6 +38,9 @@ class WidgetDecorator(object):
     """
     def __new__(cls, *args, **kwargs):
         obj = object.__new__(cls)
+        obj._format = None
+        if 'format' in kwargs:
+            obj._format = kwargs.pop('format')
         obj.data = kwargs
         try:
             return obj(args[0])
@@ -54,7 +57,7 @@ def _wrapped_view(request, *args, **kwargs):
                 self.data.update(data)
             except ValueError:
                 self.data = data
-            content, content_type = _render(request, self.data)
+            content, content_type = _render(request, self.data, self._format)
             return HttpResponse(content, content_type=content_type)
         wrapper = wraps(view_func, assigned=available_attrs(view_func))
         return csrf_exempt(wrapper(_wrapped_view))
@@ -427,11 +430,18 @@ def _is_api_key_correct(request):
     return False
 
 
-def _render(request, data):
-    """Render the data to Geckoboard based on the format request parameter."""
-    format = request.POST.get('format', '')
-    if not format:
-        format = request.GET.get('format', '')
+def _render(request, data, format=None):
+    if format:
+        if format == "json":
+            return _render_json(data)
+        else:
+            """Just default to XML"""
+            return _render_xml(data)
+    else:
+        """Render the data to Geckoboard based on the format request parameter."""
+        format = request.POST.get('format', '')
+        if not format:
+            format = request.GET.get('format', '')
     if format == '2':
         return _render_json(data)
     else:

django_geckoboard/tests/test_decorators.py

@@ -49,21 +49,41 @@ def test_wrong_api_key(self):
         self.assertTrue(isinstance(resp, HttpResponseForbidden), resp)
         self.assertEqual('Geckoboard API key incorrect', resp.content)
 
-    def test_xml_get(self):
+    def test_xml_parameter_get(self):
         req = HttpRequest()
         req.GET['format'] = '1'
         resp = widget(lambda r: "test")(req)
         self.assertEqual('<?xml version="1.0" ?><root>test</root>',
                 resp.content)
         self.assertEqual(resp._headers['content-type'], ('Content-Type', 'application/xml'))
 
-    def test_json_get(self):
+    def test_json_parameter_get(self):
         req = HttpRequest()
         req.GET['format'] = '2'
         resp = widget(lambda r: "test")(req)
         self.assertEqual('"test"', resp.content)
         self.assertEqual(resp._headers['content-type'], ('Content-Type', 'application/json'))
 
+    def test_json_get(self):
+        req = HttpRequest()
+        resp = widget(format="json")(lambda r: "test")(req)
+        self.assertEqual('"test"', resp.content)
+        self.assertEqual(resp._headers['content-type'], ('Content-Type', 'application/json'))
+
+    def test_xml_get(self):
+        req = HttpRequest()
+        resp = widget(format="xml")(lambda r: "test")(req)
+        self.assertEqual('<?xml version="1.0" ?><root>test</root>',
+                resp.content)
+        self.assertEqual(resp._headers['content-type'], ('Content-Type', 'application/xml'))
+
+    def test_wrong_format(self):
+        req = HttpRequest()
+        resp = widget(format="csv")(lambda r: "test")(req)
+        self.assertEqual('<?xml version="1.0" ?><root>test</root>',
+                resp.content)
+        self.assertEqual(resp._headers['content-type'], ('Content-Type', 'application/xml'))
+
     def test_xml_post(self):
         req = HttpRequest()
         req.POST['format'] = '1'
@@ -151,6 +171,14 @@ def test_single_value_and_parameter(self):
         json = '{"item": [{"value": 10}], "absolute": "true"}'
         self.assertEqual(json, resp.content)
 
+    def test_single_value_and_parameter_with_format(self):
+        # reset POST
+        del self.request.POST['format']
+        widget = number_widget(absolute='true', format="json")(lambda r: [10])
+        resp = widget(self.request)
+        json = '{"item": [{"value": 10}], "absolute": "true"}'
+        self.assertEqual(json, resp.content)
+
     def test_single_value_as_dictionary(self):
         widget = number_widget(lambda r: [{'value': 10}])
         resp = widget(self.request)